Hepatitis B virus (HBV) may cause acute and chronic infection of the liver. Acute hepatitis B infection may cause serious icteric hepatitis or even fulminant hepatitis, though the infection may be anicteric and asymptomatic in a high proportion of cases. Chronic hepatitis B is defined by the presence of hepatitis B surface antigen (HBsAg) in serum for longer than six months. Several hundred million people worldwide are thus infected. The expression of the disease is complex: varying levels of viral replication occur and there is a spectrum of disease ranging from benign to severe forms of chronic hepatitis. Serum aminotransferases mayor may not be elevated, and morphologic reactions in the liver range from minimal inflammatory change to destruction of hepatocytes and widespread inflammatory infiltration, cirrhosis or even hepatocellular carcinoma (HCC) (Beasley, 1988). The disease may remain clinically silent for decades but nonetheless progresses to cirrhosis and to HCC. Superinfection with hepatitis D may affect the expression of the disease. Variants of HBV infection with atypical serological markers add to the complexity of the infection. Although HBV is predominantly hepatotrophic, extrahepatic infection and complications can occur.